Comment by sidpatil
4 years ago
PowerShell takes an interesting approach in that it accepts any truncated variant of a long-form flag as a short form, provided it isn't ambiguous (i.e. if the interpreter can't decide which long-form flag to expand a short-form flag to.)
For example, if a command features a "-ConfigFile" flag, valid short-form variants include "-C", "-Co", "-Con", "-Conf", and so on. But if the command featured an additional flag "-ConfigURL" for example, the aforementioned short-form flags would be ambiguous.
getopt_long (and thus most GNU programs) work this way. I think it's probably a misfeature though since it means that adding a new option can introduce ambiguity. Having both short (ex. -x) and long (ex. --exclude) options is a less problematic solution.